As a next-generation power generation system, a fuel cell module is known that generates electric power using a hydrogen-containing gas and an oxygen-containing gas. In the fuel cell module, a plurality of solid oxide fuel cells are stacked and housed in a package in the form of a cell stack. To electrode terminals of the cell stack, bus bars are electrically connected, the bus bars being current collecting structures, and through the bus bars, electric power generated by the cell stack is supplied to the outside of the package. In general, the solid oxide fuel cells are made of ceramics.
Gaps between the package and the bus bars are enclosed with electrically insulating members. If the enclosure by the electrically insulating members is insufficient, there is the risk that carbon monoxide (CO) gas and the like leak to the outside of the package. Therefore, to enclose the gaps between the package and the bus bars sufficiently, the bus bars are fixed to a package wall of the package. In addition, for the electrically insulating members, use is made of ceramics, which have a high electrical insulating performance even at high temperatures.
However, between the cell stack that operates at high temperatures and constituting members of the fuel cell module, there is a difference in thermal expansion. Therefore, thermal stresses act on the cell stack and the electrically insulating members through the bus bars, causing the risk that the cell stack and the electrically insulating members are degraded. An objective to be achieved by the present invention is to provide a fuel cell module capable of reducing a degradation due to thermal stress.